Background The shortage of mechanical ventilators during the COVID-19 pandemic led doctors to use alternative noninvasive ventilation systems, including a modified snorkel mask. Data on the use of the modified snorkel mask is limited. Purpose The study aims to describe the effect and clinical characteristics of patients with COVID-19 treated with a snorkel mask and to investigate the factors associated with the failure to use noninvasive ventilation with a snorkel mask. Methods In this retrospective observational study, adult patients with COVID-19 who were treated with a snorkel mask at Daniel Alcides Carrion Hospital of Huancayo-Perú were selected. Results Of the 390 patients included, 158 (20.5%) received noninvasive ventilation with a snorkel, 84 (53.2%) patients were discharged alive without intubation, and the mortality rate was 22%. In the control group that received standard treatment, 129 patients (55.6%) failed (i.e., deceased or admitted to a mechanical ventilator). The mortality rate was 33.2%. ROX index < 4.8, consolidation-type tomographic pattern, and the presence of complications, such as bacterial pneumonia or thromboembolism, were independently associated with a higher risk of noninvasive ventilation failure with snorkels. Conclusions Using the snorkel system resulted in an absolute mortality reduction of 11%, and recovery increased by 15% compared to the standard treatment system. Therefore, this device can be used as an acceptable alternative in the absence of mechanical ventilators.